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Objective

The transport sector represents a growing share of the total fossil fuel usage in the world. In order to fulfil the commitment to the Kyoto Protocol, the world usage of fossil oil in transport sectors must be reduced. One important approach to achieving this goal is to increase the share of renewable sources such as feedstocks in conversion routes. These biomass conversion routes involve a number of difficulties that should be attended to first by a suitable process configuration to avoid catalyst poisoning in production of syngas. Second, a major problem in the production of syngas-derived fuel from renewable sources is the presence of contaminates in the product gas from biomass gasifiers. These impurities that cause catalytic poisoning should be completely removed prior to the entry in catalytic systems that utilize in upgrading steps. With the evolution of these advanced uses of biomass derived syngas, it becomes necessary to develop progressively more stringent gas cleaning systems. Therefore, the project's key goal is development of a novel gas cleanup in order to reduce impurities from the gasifier’s product gas to limits required for upgrading to syngas using as a feedstock in production of vehicle fuels. To accomplish this target that biomass conversion should preserve high energy efficiency in the subsequent synthesis steps and prevent catalytic poisoning, an alternative product route and more efficient gas cleaning systems are required. Nevertheless, biomass conversion processes offer many economical and environmental benefits, but it is clear that conversion technology should be able to compete with other conversion routes, for example via methane. Therefore, this RTD programme combines European expertise in the field of gasification, different proficiencies in cleaning technologies, high ranking catalyst expertise, catalyst company, and two research companies with R&D activities in the fields to expedite the development and commercialization of research outcomes.

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Cleaning biomass-derived gas for biofuels

In the quest to fulfil commitments to the Kyoto Protocol, biomass feedstocks have been found to represent a viable alternative to fossil fuel sources. To build on their potential, scientists set out to devise technologies for the removal of impurities and contaminants during processing.

As part of the EU-funded 'Advanced cleaning devices for production of green syngas' (GREENSYNGAS) project, researchers made substantial progress towards this goal. For example, one of the project partners managed to develop novel filtering systems to remove particles from biomass-derived synthesis gas (syngas). The idea was to create syngas pure enough for conversion into biofuels for the transport sector and electricity generation, among other uses.
Three techniques were developed. The first used physical removal of tars and another utilised catalytic reforming of the tar contaminants. A third system employed oxidative thermal treatment.
These promising prototypes fulfilled the aim of the project: to develop and demonstrate advanced syngas cleaning technologies using both chemical and physical methods.
The research drew on the expertise of those in the fields of gasification, cleaning technologies, catalysts, and product development and commercialisation. Project efforts resulted in a number of journal publications and results have been presented at 20 international conferences.
Further research will determine if this system and others investigated in the laboratory can be up-scaled for real-world applications. Biomass conversion processes offer many environmental and economic benefits. GREENSYNGAS has added a very necessary building block to this area of research and it is hoped that further studies could even result in commercialisation.

Final Report Summary - GREENSYNGAS (Advanced cleaning devices for production of green syngas)

The GREENSYNGAS project has dealt with advanced upgrade and cleaning techniques for biomass- generated synthesis gas by gasification. The aim has been first of all to demonstrate new and innovative techniques and processes in different states, such as proof of concept, laboratory and pilot scale demonstrations. Techniques and processes demonstrated in the project belong to one, two or all of the three fundamentally different predefined process configurations. The first one was based on physical removal and utilisation of the tars in the producer gas. The second was based on oxidative thermal treatment, i.e. partial oxidation, of the producer gas and the third configuration was based on catalytic reforming of the tars. Among the demonstrations were techniques and systems for high temperature particulate removal, high temperature sulfur, chlorine and alkali absorption in bed tar removal, selective ammonia (NH3)oxidation, new techniques for online tar, particulate and alkali measurement, regenerative partial oxidation, water gas shift, new catalytic materials for tar reforming, etc.

As a complication in the project, the original pilot demonstration site, Växjö Värnamo Biomass Gasification (VVBG) with its gasifier in Värnamo, Sweden, withdrew from the project and was replaced by Biomasse Kraftwerk Güssing (BKG) Güssing. Due to the difference in technology between the two sites, Värnamo pressurised and Güssing atmospheric, it became very difficult to supply the already planned demonstration activities with correct working conditions. Some of the demonstration activities had to be moved to other locations, for instance to the gasifiers at Delft University of technology (TUD) and Munich, while others had to be performed in the laboratories at Norwegian University of science and technology (NTNU) in Trondheim and Lund University (ULUND) in Lund. To overcome the problems, and make it possible to realise the pilot demonstration of high temperature particulate removal system, Porvair begun the construction of an educator and heating system, to boost the pressure. This work was not included in the original project description and no financial means were allocated for this purpose. Due to delays caused by the highly specialised parts of this system, it was not possible to finalise the system during the project time. The particulate cleaning system was demonstrated on a laboratory scale with excellent results, but due to the time frame of the project the pilot demonstration was not carried out.

An active dissemination of information has taken place during the project time: nine journal papers have been published, and more are planned. The results from the project have been presented at 20 international conferences. The results from the project will probably impact the technique development in Europe and there are expected commercialisations of technique developed in the project, for instance, the high-temperature particulate removal system. Flowsheeting based on the partner's outcome of research was evaluated by Johnson Matthew (JM) and the results are considered as significant part of the exploitation that bring the conversion routes of biomass to biofuels closer to the market.

Project context and objectives:

The main aim of the project was to develop and demonstrate advanced (bio) synthesis gas cleaning technologies based on physical separation (a combination of an optimised cyclone and sintered metal filter) and chemical conversion (in situ capture). The purified syngas produced would then be suitable for a number of downstream applications including conversion into synthetic biofuels for the transport sector, hydrogen, or electricity generation with carbon capture and storage (CCS).

The resultant producer gas arising from the gasification of a biomass feedstock contains - to different extents depending on gasifier conditions - both particulate and gaseous contaminants that can have a deleterious impact on the performance of downstream catalysts and metallurgy. Two of the most important contaminants necessary to address are condensable tars and alkalis; other contaminants of relevance to catalyst performance include NH3, HCl, particulates and sulfur-containing molecules. Thus, for biomass feedstocks, advances are required in the gas cleanup technologies and associated processes to upgrade the raw producer gas. A key requisite for these operations is that they have a minimal impact on the overall efficiency of the process, such as not requiring a significant amount of additional heating and electrical energy consumption.

A key aspect of the project was the demonstration of a selection of the technologies that were developed. From the initial laboratory testing, it was intended that some of the technologies, including a novel high-temperature particulate removal system, would be demonstrated at the combined heat and power (CHP) demo plant at BKG in Austria. This was an important criterion for assessing the technical viability and potential commercialisation of the technologies.

Addressing the scientific objectives of the project: Three configurations for the downstream processing of producer gas were proposed and are described later in this summary. The project's objectives relate to the operations making up these configuration options.

One challenge addressed in this project was the characterisation of the producer gas. When dealing with tars and particulate matter, this poses a significant problem, especially when an in situ measurement has to be taken under plant-operating conditions.

Particulate removal is necessary and conducting this operation at a high temperature has the benefit of maintaining process efficiency. A novel particulate removal system, fundamentally comprised of a cyclone and filter unit, was developed by one of the project partners for trial testing. A number of filter elements were tested as part of the project. Tar mitigation via reaction and necessary catalyst poison removal was a major aspect for the project consortium to address.